Enhanced photodynamic therapy and fluorescence imaging using gold nanorods for porphyrin delivery in a novel in vitro squamous cell carcinoma 3D model

Multifunctional gold nanoparticles for cancer theranostics

The diagnosis and treatment of cancer can often be challenging requiring more attractive options. Some types of cancers are more aggressive than others and symptoms for many cancers are subtle, especially in the early stages. Nanotechnology provides high sensitivity, specificity and multimodal capability for cancer detection, treatment and monitoring. In particular, metal nanoparticles (NPs) such as gold nanoparticles (AuNPs) are attractive nanosystems for researchers interested in bioimaging and therapy. The size, shape and surface of AuNPs can be modified for improving targeting and accumulation in cancer cells, for example through introduction of ligands and surface charge. The interactions of AuNPs with electromagnetic radiation (e.g., visible-near-infrared, X-rays) can be used for photothermal therapy and radiation therapy, through heat generated from light absorption and emission of Auger electrons, respectively. The subsequent expansion and high X-ray attenuation from AuNPs can be used for enhancing contrast for tumor detection (e.g., using photoacoustic, computed tomography imaging). Multi-functionality can be further extended through covalent/non-covalent functionalization, for loading additional imaging/therapeutic molecules for combination therapy and multimodal imaging. In order to cover the important aspects for designing and using AuNPs for cancer theranostics, this review focuses on the synthesis, functionalization and characterization methods that are important for AuNPs, and presents their unique properties and different applications in cancer theranostics.

Gold nanorods as biocompatible nano-agents for the enhanced photothermal therapy in skin disorders

Rod-shaped gold nanomaterials, known as gold nanorods (GNRs), may undergo specific surface alterations, because of their straightforward surface chemistry. This feature makes them appropriate for use as functional and biocompatible nano-formulations. By optimizing the absorption of longitudinally localized surface plasmon resonance (LSPR) in the near-infrared (NIR) region, which corresponds to the NIR bio-tissue window, GNRs with appropriate modifications may improve the results of photothermal treatment (PTT). In dermatology, potential noninvasive uses of GNRs to enhance wound healing, manage infections, combat cutaneous malignancies, and remodel skin tissues via PTT have attracted research attention in recent years. In this review, the basic properties of GNRs, such as shape, size, optical performance, photothermal efficiency, and metabolism, are discussed firstly. Then, the disadvantages of using these particles in photodynamic therapy (PDT) are proposed. Next, biological applications of GNRs-based PTT are summarized in detail. Finally, the limitations and future perspectives of this research are summarized, providing a comprehensive outlook for prospective GNRs with PTT.

Porphyrin as a Cryoprotectant for Graphene Oxide-Coated Gold Nanorods to Produce Conjugated Product with Improved Stability and Opto-Phototherapeutic Properties

Graphene oxide (GO) as a coating material for gold nanorods (AuNRs) has gained interest in reducing toxicity and improving the photothermal profiling of AuNRs. However, there is still a challenge regarding the storage of colloidal suspensions of GO-coated AuNRs (GO@AuNRs). Hence, the conjugation of GO@AuNRs to meso-tetra-(4-sulfonatophenyl)porphyrin (TPPS4), an anionic water-soluble porphyrin, has been reported to enhance their re-dispensability and improve their phototherapeutic properties. The AuNRs and GO were synthesised using seed-mediated and Hummers' methods, respectively. The GO@AuNRs were conjugated to TPPS4 and characterised using ultraviolet-visible-near-infrared (UV-Vis-NIR) spectroscopy, zeta analyser, dynamic light scattering (DLS), photoluminescence spectroscopy (PL), x-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and Fourier-transform infrared spectroscopy (FTIR) before freeze-drying. The results showed that the AuNRs were sandwiched between GO and TPPS4. After freeze-drying, the freeze-dried conjugate was dispensed in deionised water without adding cryoprotectants and its properties were compared to those of the unfreeze-dried conjugate. The results showed that the freeze-dried conjugate contained similar optical properties to the unfreeze-dried conjugate. However, the bare GO@AuNRs showed a change in the optical properties after freeze-drying. These results revealed that porphyrin is an excellent additive to reduce the freeze-drying stress tolerance of GO@AuNRs. The freeze-dried conjugate also showed both singlet oxygen and photothermal properties of GO@AuNRs and porphyrin. These results indicated that the freeze-dried conjugate is a promising dual photodynamic and photothermal agent, and porphyrin can act as a cryoprotectant.

Enhanced Photodynamic Therapy by Improved Light Energy Capture Efficiency of Porphyrin Photosensitizers

OPINION STATEMENT

Photodynamic therapy (PDT) has garnered increasing attention in cancer treatment because of its advantages such as minimal invasiveness and selective destruction. With the development of PDT, impressive progress has been made in the preparation of photosensitizers, particularly porphyrin photosensitizers. However, the limited tissue penetration of the activating light wavelengths and relatively low light energy capture efficiency of porphyrin photosensitizers are two major disadvantages in conventional photosensitizers. Therefore, tissue penetration needs to be enhanced and the light energy capture efficiency of porphyrin photosensitizers improved through structural modifications. The indirect excitation of porphyrin photosensitizers using fluorescent donors (fluorescence resonance energy transfer) has been successfully used to address these issues. In this review, the enhancement of the light energy capture efficiency of porphyrins is discussed.

A Genetic Algorithm for Universal Optimization of Ultrasensitive Surface Plasmon Resonance Sensors with 2D Materials

We present a general optimization technique for surface plasmon resonance, (SPR) yielding a range of ultrasensitive SPR sensors from a materials database with an enhancement of ∼100%. Applying the algorithm, we propose and demonstrate a novel dual-mode SPR structure coupling SPP and a waveguide mode within GeO2 featuring an anticrossing behavior and an unprecedented sensitivity of 1364 deg/RIU. An SPR sensor operating at wavelengths of 633 nm having a bimetal Al/Ag structure sandwiched between hBN can achieve a sensitivity of 578 deg/RIU. For a wavelength of 785 nm, we optimized a sensor as a Ag layer sandwiched between hBN/MoS2/hBN heterostructures achieving a sensitivity of 676 deg/RIU. Our work provides a guideline and general technique for the design and optimization of high sensitivity SPR sensors for various sensing applications in the future.

Porphin e6 complex loaded with gold nanorod mesoporous silica enhances photodynamic therapy in ovarian cancer cells in vitro

A growing amount of experimental evidence has proven that the application of gold nanorods (AuNRs) in photodynamic therapy (PDT) can significantly enhance its therapeutic efficacy. The aim of this study was to establish a protocol for investigating the effect of gold nanorods loaded with the photosensitizer chlorin e6 (Ce6) on photodynamic therapy in the OVCAR3 human ovarian cancer cell line in vitro and to determine whether the PDT effect was different from that of Ce6 alone. OVCAR3 cells were randomly divided into three groups: the control group, Ce6-PDT group, and AuNRs@SiO₂@Ce6-PDT group. Cell viability was measured by MTT assay. The generation of reactive oxygen species (ROS) was measured by a fluorescence microplate reader. Cell apoptosis was detected by flow cytometry. The expression of apoptotic proteins was detected by immunofluorescence and western blotting. The results showed that compared with that of the Ce6-PDT group, the cell viability of the AuNRs@SiO₂@Ce6-PDT group was significantly decreased (P < 0.05) in a dose-dependent manner, and ROS production increased significantly (P < 0.05). The flow cytometry results showed that the proportion of apoptotic cells in the AuNRs@SiO₂@Ce6-PDT group was significantly higher than that in the Ce6-PDT group (P < 0.05). Immunofluorescence and western blot results showed that the protein expression levels of cleaved caspase-9, cleaved caspase-3, cleaved PARP, and Bax in the AuNRs@SiO₂@Ce6-PDT-treated-OVCAR3 cells were higher than those in the Ce6-PDT-treated cells (P < 0.05), and the protein expression levels of caspase-3, caspase-9, PARP, and Bcl-2 were slightly lower than those in the Ce6-PDT group (P < 0.05). In summary, our results show that AuNRs@SiO₂@Ce6-PDT has a significantly stronger effect on OVCAR3 cells than the effect of Ce6-PDT alone. The mechanism may be related to the expression of Bcl-2 family and caspase family in the mitochondrial pathway.

Insights into Gold Nanoparticles Possibilities for Diagnosis and Treatment of the Head and Neck Upper Aerodigestive Tract Cancers

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer affecting people and accounts for more than 300,000 deaths worldwide. Improvements in treatment modalities, including immunotherapy, have demonstrated promising prognoses for eligible patients. Nevertheless, the five-year overall survival rate has not increased significantly, and the tumor recurrence ratio remains at 50% or higher, except for patients with HPV-positive HNSCC. Over the last decades, nanotechnology has provided promising tools, especially for biomedical applications, due to some remarkable physicochemical properties of numerous nanomaterials, particularly gold nanoparticles. This review addresses the features and some applications of gold nanoparticles reported in the literature over the last five years regarding the diagnosis and treatment of head and neck cancer, highlighting the exciting possibilities of this nanomaterial in oncology.

METHODS

The scientific papers selected for this review were obtained from the PubMed Advanced, Web of Science, Scopus, ClinicalTrials.gov, and Google Scholar platforms.

CONCLUSIONS

Results from papers applying gold nanoparticles have suggested that their application is a feasible approach to diagnostics, prognostics, and the treatment of HNC. Moreover, phase I clinical trials suggest that gold nanoparticles are safe and can potentially become theranostic agents for humans.

An Overview on Gold Nanorods as Versatile Nanoparticles in Cancer Therapy

Gold nanorods (GNRs/AuNRs) are a group of gold nanoparticles which their simple surface chemistry allows for various surface modifications, providing the possibility of using them in the fabrication of biocompatible and functional nano-agents for cancer therapy. AuNRs, moreover, exhibit a maximum absorption of longitudinal localized surface plasmon resonance (LSPR) in the near-infrared (NIR) region which overlaps with NIR bio-tissue 'window' suggesting that they are proper tools for thermal ablation of cancer cells. AuNRs can be used for induction of mono or combination therapies by administering various therapeutic approaches such as photothermal therapy (PTT), photodynamic therapy (PDT), chemotherapy (CT), radiotherapy (RT), and gene therapy (GT). In this review, anticancer therapeutic capacities of AuNRs along with different surface modifications are summarized comprehensively. The roles of AuNRs in fabrication of various nano-constructs are also discussed.

Porphyrin-Based Nanoparticles: A Promising Phototherapy Platform

Phototherapy, including photodynamic therapy and photothermal therapy, is an emerging form of non-invasive treatment. The combination of imaging technology and phototherapy is becoming an attractive development in the treatment of cancer, as it allows for highly effective therapeutic results through image-guided phototherapy. Porphyrins have attracted significant interest in the treatment and diagnosis of cancer due to their excellent phototherapeutic effects in phototherapy and their remarkable imaging capabilities in fluorescence imaging, magnetic resonance imaging and photoacoustic imaging. However, porphyrins suffer from poor water solubility, low near-infrared absorption and insufficient tumor accumulation. The development of nanotechnology provides an effective way to improve the bioavailability, phototherapeutic effect and imaging capability of porphyrins. This review highlights the research results of porphyrin-based small molecule nanoparticles in phototherapy and image-guided phototherapy in the last decade and discusses the challenges and directions for the development of porphyrin-based small molecule nanoparticles in phototherapy.

Tissue Engineering and Photodynamic Therapy: A New Frontier of Science for Clinical Application -An Up-To-Date Review

Tissue engineering (TE) connects principles of life sciences and engineering to develop biomaterials as alternatives to biological systems and substitutes that can improve and restore tissue function. The principle of TE is the incorporation of cells through a 3D matrix support (scaffold) or using scaffold-free organoid cultures to reproduce the 3D structure. In addition, 3D models developed can be used for different purposes, from studies mimicking healthy tissues and organs as well as to simulate and study different pathologies. Photodynamic therapy (PDT) is a non-invasive therapeutic modality when compared to conventional therapies. Therefore, PDT has great acceptance among patients and proves to be quite efficient due to its selectivity, versatility and therapeutic simplicity. The PDT mechanism consists of the use of three components: a molecule with higher molar extinction coefficient at UV-visible spectra denominated photosensitizer (PS), a monochromatic light source (LASER or LED) and molecular oxygen present in the microenvironment. The association of these components leads to a series of photoreactions and production of ultra-reactive singlet oxygen and reactive oxygen species (ROS). These species in contact with the pathogenic cell, leads to its target death based on necrotic and apoptosis ways. The initial objective of PDT is the production of high concentrations of ROS in order to provoke cellular damage by necrosis or apoptosis. However, recent studies have shown that by decreasing the energy density and consequently reducing the production of ROS, it enabled a specific cell response to photostimulation, tissues and/or organs. Thus, in the present review we highlight the main 3D models involved in TE and PS most used in PDT, as well as the applications, future perspectives and limitations that accompany the techniques aimed at clinical use.

Merging Porphyrins with Gold Nanorods: Self Assembly Construct to High Fluorescent Polyelectrolyte Microcapsules

Dual probe porphyrin-gold nanorod polyelectrolyte microcapsules were developed to explore the enhancing effects of a plasmonic interface of self-assembled gold nanoparticles in the fluorescence emission from porphyrins loaded into the capsules' core. An analysis of fluorescence lifetime imaging microscopy (FLIM) data reports a notable 105-106-fold increase in the maximum detected photon rates from diffraction-limited spots and an overall six-fold increase in fluorescence as averaged over the whole microcapsule area. Large emission enhancements were correlated with decreases in fluorescence lifetimes. The microcapsule's design proved effective in achieving high fluorescent hybrids and may shed light on new possibilities for advanced materials imaging applications.

N-Doped Graphene Quantum Dots/Titanium Dioxide Nanocomposites: A Study of ROS-Forming Mechanisms, Cytotoxicity and Photodynamic Therapy

Titanium dioxide nanoparticles (TiO2 NPs) have been proven to be potential candidates in cancer therapy, particularly photodynamic therapy (PDT). However, the application of TiO2 NPs is limited due to the fast recombination rate of the electron (e-)/hole (h+) pairs attributed to their broader bandgap energy. Thus, surface modification has been explored to shift the absorption edge to a longer wavelength with lower e-/h+ recombination rates, thereby allowing penetration into deep-seated tumors. In this study, TiO2 NPs and N-doped graphene quantum dots (QDs)/titanium dioxide nanocomposites (N-GQDs/TiO2 NCs) were synthesized via microwave-assisted synthesis and the two-pot hydrothermal method, respectively. The synthesized anatase TiO2 NPs were self-doped TiO2 (Ti3+ ions), have a small crystallite size (12.2 nm) and low bandgap energy (2.93 eV). As for the N-GQDs/TiO2 NCs, the shift to a bandgap energy of 1.53 eV was prominent as the titanium (IV) tetraisopropoxide (TTIP) loading increased, while maintaining the anatase tetragonal crystal structure with a crystallite size of 11.2 nm. Besides, the cytotoxicity assay showed that the safe concentrations of the nanomaterials were from 0.01 to 0.5 mg mL-1. Upon the photo-activation of N-GQDs/TiO2 NCs with near-infrared (NIR) light, the nanocomposites generated reactive oxygen species (ROS), mainly singlet oxygen (1O2), which caused more significant cell death in MDA-MB-231 (an epithelial, human breast cancer cells) than in HS27 (human foreskin fibroblast). An increase in the N-GQDs/TiO2 NCs concentrations elevates ROS levels, which triggered mitochondria-associated apoptotic cell death in MDA-MB-231 cells. As such, titanium dioxide-based nanocomposite upon photoactivation has a good potential as a photosensitizer in PDT for breast cancer treatment.

Non-Oncologic Applications of Nanomedicine-Based Phototherapy

Phototherapy is widely applied to various human diseases. Nanomedicine-based phototherapy can be classified into photodynamic therapy (PDT) and photothermal therapy (PTT). Activated photosensitizer kills the target cells by generating radicals or reactive oxygen species in PDT while generating heat in PTT. Both PDT and PTT have been employed for treating various diseases, from preclinical to randomized controlled clinical trials. However, there are still hurdles to overcome before entering clinical practice. This review provides an overview of nanomedicine-based phototherapy, especially in non-oncologic diseases. Multiple clinical trials were undertaken to prove the therapeutic efficacy of PDT in dermatologic, ophthalmologic, cardiovascular, and dental diseases. Preclinical studies showed the feasibility of PDT in neurologic, gastrointestinal, respiratory, and musculoskeletal diseases. A few clinical studies of PTT were tried in atherosclerosis and dry eye syndrome. Although most studies have shown promising results, there have been limitations in specificity, targeting efficiency, and tissue penetration using phototherapy. Recently, nanomaterials have shown promising results to overcome these limitations. With advanced technology, nanomedicine-based phototherapy holds great potential for broader clinical practice.

Design of ZIF-based hybrid nanoparticles with hyaluronic acid-augmented ROS behavior for dual-modality PA/NIR-II FL imaging

Photoacoustic (PA) imaging has emerged as a promising bio-imaging technique due to its non-invasive visualization of lesions at great penetration depths. Fluorescence (FL) imaging in the second near-infrared window (NIR-II, 1000-1700 nm) achieves a higher imaging resolution and lower background signals compared to NIR-I. However, the single imaging method possesses its own disadvantages. Thus, we have demonstrated ZIF-8-IR820-MnPc-HA nanoparticles (ZIMH NPs) that can achieve visualization and localization of tumors in mice models with the help of a dual-modality PA/NIR-II FL imaging performance. Meanwhile, these excellent nanoparticles also induce the efficient generation of singlet oxygen (1O2) upon 808 nm laser illumination, and display excellent photodynamic therapy efficacy in cells, further indicating their potential application for in vivo PDT. In ZIMH NPs, hyaluronic acid (HA) impressively acts as a "sponge", enhancing the generation of 1O2 and facilitating the cellular therapeutic effects. We believe that ZIF-8-IR820-MnPc-HA NPs present a brand-new strategy for the exploration of efficient PDT photosensitizers with dual-modality imaging performance for use in various biomedical applications.